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(Delphi DLL) Decrypt S/MIME and Verify S/MIME SignaturesDelphi DLL example to decrypt S/MIME and verify S/MIME signatures. The S/MIME is unwrapped to get the original MIME prior to signing/encrypting. Note: This example requires Chilkat v11.0.0 or greater.
uses Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Cert, Mime; ... procedure TForm1.Button1Click(Sender: TObject); var success: Boolean; mime: HCkMime; isEncrypted: Boolean; isSigned: Boolean; signerCert: HCkCert; decryptCert: HCkCert; begin success := False; // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. mime := CkMime_Create(); // Load an S/MIME message from a file: success := CkMime_LoadMimeFile(mime,'signedMime.txt'); if (success = False) then begin Memo1.Lines.Add(CkMime__lastErrorText(mime)); Exit; end; // The ContainsEncryptedParts/ContainsSignedParts methods // can be called to determine if the MIME is encrypted and/or signed: isEncrypted := CkMime_ContainsEncryptedParts(mime); isSigned := CkMime_ContainsSignedParts(mime); // We don't want the "unwrap extras". You'll see what those // are in a few moments... CkMime_putUnwrapExtras(mime,False); // To verify the signature, call UnwrapSecurity. This will // verify the signature(s) and decrypt the S/MIME and restore // the MIME to the unsigned/unencrypted state. // The results of what was found are present in the MIME object's // properties, as well as extra header fields that are added // to the unwrapped MIME. success := CkMime_UnwrapSecurity(mime); if (success <> True) then begin // UnwrapSecurity returns True if all signatures were // verified and all parts decrypted. Memo1.Lines.Add(CkMime__lastErrorText(mime)); Exit; end; // The mime.UnwrapExtras property controls whether or not // these additional fields are added to the unwrapped MIME: // // X-NumPartsSigned: 1 // X-SignaturesValid: yes // X-NumPartsEncrypted: 1 // X-Decrypted: no // // The X-NumPartsSigned/X-SignaturesValid headers are added // if the MIME was signed. // // The X-NumPartsEncrypted/X-Decrypted headers are added // if the MIME was encrypted. // // If the MIME was signed, get the certificate used for signing. if (isSigned = True) then begin signerCert := CkCert_Create(); // The NumSignerCerts property indicates how many certificates // were used for signing. This example will assume the value is 1. // To get the 1st signer cert, call LastSignerCert with an index of 0: success := CkMime_LastSignerCert(mime,0,signerCert); if (success = True) then begin Memo1.Lines.Add('**** Signer Cert: ' + CkCert__subjectCN(signerCert)); end; end; // If the MIME was encrypted, get the certificate used for decryption if (isEncrypted = True) then begin // The NumDecryptCerts property indicates how many certificates // were used for decrypting. This example will assume the value is 1. // To get the 1st decrypt cert, call LastDecryptCert with an index of 0: decryptCert := CkCert_Create(); success := CkMime_LastDecryptCert(mime,0,decryptCert); if (success = True) then begin Memo1.Lines.Add('**** Decrypt Cert: ' + CkCert__subjectCN(decryptCert)); end; end; // Display the unwrapped MIME: Memo1.Lines.Add(CkMime__getMime(mime)); // Save the unwrapped MIME to a file: success := CkMime_SaveMime(mime,'unwrappedMime.txt'); CkMime_Dispose(mime); CkCert_Dispose(signerCert); CkCert_Dispose(decryptCert); end; |
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